package com.fzj.example.test;

import java.util.Hashtable;
import java.util.concurrent.ConcurrentHashMap;

public class Case {
    public static void main(String[] args) {
        Hashtable<String,String> ht=new Hashtable<>();
        ht.put(null,null);
        ConcurrentHashMap concurrentHashMap=new ConcurrentHashMap();
        concurrentHashMap.put(null,null);
    }
}
